1. Field of the Invention
The invention relates to an apparatus for the damping of impacts, preferably the impacts of furniture doors or drawers, consisting of a cylinder with a piston whose piston rod sealingly guided out of a cylinder side forms a ram absorbing the impacts which divides the cylinder space filled with a liquid into two chambers and has perforations and/or, together with the cylinder wall, bounds a passage gap, of a bushing arranged in the region of the outlet end of the cylinder and guiding the piston rod, and of a compression spring clamped between the piston and the cylinder bottom.
2. Description of the Related Art
Damping apparatuses of this kind have either a complicated construction or they are large in dimension or they do not guarantee a smooth and quiet running. Rough running and irritating noises can be caused in particular by the air bubbles present in the damping liquid.
It is therefore the object of the invention to provide a damping apparatus of the kind first given which ensures a smooth and quiet running with a construction which is as compact as possible.
In accordance with the invention, this object is solved in a damping apparatus of the kind initially given by the bushing having a central shaft part of reduced diameter and by a widened end part thereof being supported on a step or an annular flange constricting the inner diameter of the cylinder and, the other end being supported on a cover closing the cylinder and by the shaft part being enclosed by a tube-section-like part made of elastic material.
The damping apparatus in accordance with the invention can be made in a small and compact construction due to its parts to be dimensioned. The tube-section-like part made of elastic material is located in the cylinder chamber on the piston rod side in which the air bubbles collect without interference in a dead space. The air bubbles can also be absorbed without interference by the tube-section-like part which simultaneously forms a storage bush.
The tube-section-like part forming the storage bush can consist of cellular rubber or foam rubber or of foamed elastomer plastic. It should preferably have closed cells so that it can be highly compressed.
The cover appropriately consists of a bush-shaped part with a borehole in its bottom for the passage of the piston rod and with a flange-shaped edge via which the cover is supported on the annular end face of the cylinder. To connect the cover to the cylinder, the two can, if they consist of plastic, be connected by an ultrasonic welding connection. The connection can naturally also be made in any other manner, for example by adhesive bonding.
The bushing can be supported on the cover with a part widening the shaft part. Appropriately, the bushing grips into the cover with a frusto-conically shaped widening part. The widening part of the bushing can also be supported on an annular step of the inner space of the cover.
In another aspect of the invention, it is provided that an annular lip seal is held between the bottom of the cover and the annular end face of the bushing, said lip seal preventing a discharge of the liquid, preferably oil.
In another aspect of the invention, it is provided that the bushing is provided with radial ribs at its end region at the cover side. The tube-section-like storage bush is then supported on axially extending ends of these ribs so that a storage space for any air bubbles is formed between the ribs.
The lower widened part of the bushing can be provided with perforations or sections which bound the passage gap together with the cylinder wall.
Appropriately, the piston rod in the cylinder is provided with a flat head with which it is supported on the piston. The piston itself is provided with perforations or bounds a ring gap together with the cylinder wall.
The piston preferably has a transversely extending groove with an axial borehole in its end face facing the piston rod, which opens into a widened axial borehole. The piston can be provided with at least one radial borehole which connects the axial borehole to a widened piston section. Furthermore, the piston can be reduced in its diameter on its side facing the cylinder bottom so that a seating is formed for the compression spring.
In another embodiment of the invention, it is provided that the piston has an annular groove between its end face and its widened part and that a slit ring is inserted into the annular groove. This slit ring is expanded under the pressure of the damping liquid and then improves the guiding of the piston in the cylinder, with the expanded slit then forming an additional constricting passage for the damping liquid.